1. Field of the Invention
The present invention relates to a high-speed rod mill and wire mill for single-strand, twist-free rolling of material. The rod mill and wire mill includes a roughing train, at least one intermediate train and a subsequent finishing train, wherein each of the trains include several rolling mill stands or rolling units, and possibly a subsequent finishing stand set.
2. Description of the Related Art
The development of rolled wire production has been very rapid in recent years due to the use of new technologies, such as, Morgan blocks and Stelmor cooling units. For example, the maximum speeds were increased from about 35 m/s to more than 100 m/s; the initial pass cross-sections were increased from 80 mm diameters to up to 150 mm diameters. The collar sizes were increased threefold. As a consequence of this development, it was possible to switch from four-strand and three-strand trains to two-strand or single-strand trains with all the attendant advantages with respect to yields and utilization of the production plants.
Concerning the arrangement of the rolling mill stands it is to be noted that in the case of normal steel qualities the continuous horizontal stand arrangement was chosen for the roughing train as well as for the intermediate train particularly in the case of contemplated multiple-strand rolling. In this arrangement, it is necessary to twist between the stands depending upon the pass shape. The requirements made with respect to surface quality and tolerances in most cases permit such a manner of operation.
In those cases in which higher requirements are made, the intermediate trains are frequently split and are equipped with stands in horizontal/vertical arrangement with the appropriate units for tension-free rolling. This is particularly important for the production of Garret sizes with good surfaces and tolerances.
For moderately alloyed steels and high-alloy steels and grades with particular surface qualities, a horizontal/vertical arrangement is needed for the entire rolling mill train because these qualities in most cases no longer permit twisting. In order to be complete, it is noted that for obtaining a good surface quality, roller guides are usually used between the stands.
Depending on the wire qualities to be rolled, various twist-free finishing stand set constructions were also developed. The individual horizontal/vertical roll units of the finishing stand sets have cantilevered hard metal collars.
With respect to the present situation of the technological development of wire mills it is to be noted that these mills more and more must be developed in accordance with the specific requirements of the operator because the degree of utilization of the wire mill should be increased and the wire mill should be adaptable to the respective production programs. Also, the yields are to be increased and the high quality of the product is to be ensured.